Decades of research have highlighted the damaging effects of disadvantaged neighborhood contexts on later health outcomes, including youth antisocial behaviors (ASB) such as assault, theft, and vandalism. Although few would now contest the behavioral sequelae of neighborhood disadvantage, the mechanism(s) driving these effects are as yet unclear. A major focus of the parent grant is to understand how social processes in the home (parenting) and physical processes in the environment (toxicants) undermine brain development (across structure and function). The current supplement application aims to deepen the focus of this study on the social processes in the neighborhood that affect the activation of the amygdala and broader corticolimbic circuit ? a critical neural regions for the initiation and regulation of the stress response. By examining social factors in the neighborhood (lack of social cohesion, exposure to violence) that may undermine the development of stress-related neural functioning, the proposed supplement will use a genetically-informed developmental neuroscience approach to understand how the broader social context outside of the home may undermine development. Through the use of a twin sample, the proposed project will leverage twin differences to identify causal mechanisms affecting brain development. Moreover, through this project, a PhD student will gain cutting-edge, interdisciplinary training in functional neuroimaging, behavior genetics, and neighborhood effects, in a way that will continue her strong academic trajectory and uniquely position her for a novel, research focused career with training well outside of the typical course of study. This training will position this student well for future funding (F, K, R series) by establishing her skills across multiple disciplines. Thus the proposed study will enhance the Aims of the parent grant, while providing unique training for a talented junior researcher who will add diversity to the scientific community.